Fuel system and method of operation



June 4, 1968 w DRAYER 3,386,709

FUEL SYSTEM AND METHOD OF OPERATION Filed Sept. 16, 1965 l N VEN TOR.

A TTORNEV United States Patent 3,386,709 FUEL SYSTEM AND METHOD OF OPERATEUN William L. Drayer, Warren, Micln, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Filed Sept. 16, 1965, Ser. No. 487,757 12 Claims. (Cl. 261-29) This invention relates to fuel systems and is particularly directed to fuelsystems utilizing fluid amplifier technology.

Because spark ignition internal combustion engines are quite sensitive to the proportions of the air-fuel mixture in the combustion chamber, innumerable systems have been developed in attempts to supply the engine with an air-fuel mixture proper for the various operating conditions. The systems in common use, however, include a venturi located in the air inlet to create a pressure signal which varies with the rate of air flow to the engine; this pressure signal determines the rate at which fuel is delivered to the engine.

Unfortunately however, the venturi signal does not vary linearly with air flow. When utilizing a large venturi to avoid restricting air flow at high air flow rates, the venturi signal is very weak at low air flow rates. This weak signal would result in insufficient fuel delivery to the engine. On the other hand, a small venturi which would provide an adequate fuel metering signal at low air flow rates would also restrict air flow at high air flow rates. For these reasons, a compromise is generally adopted in which a separate idle system provides fuel at the lowest air flow rates, a large venturi and one or two smaller boost venturi provide a fuel metering signal over the part throttle and wide-open throttle operating ranges, and off-idle discharge ports smooth the transition from the idle system to the venturi metering system as the throttle opens.

This invention makes unnecessary such a complex arrangement by providing an unusually simple but effective means for amplifying the signal which indicates the air flow rate. Using the principles of the recently announced fluid amplifiers, weak control signals such as venturi pressure are amplified to produce control signals strong enough to meter fuel throughout the range of engine operating conditions.

As more extensively discussed in recent literature, Control Engineering of January 1963, for example, a fluid amplifier uses a relatively weak control signal to deflect the path of a fluid stream. Because relatively large deflections in the fluid path are obtained with weak control signals, a more sensitive control function is obtained by measuring the deflection of the path rather than by directly measuring the control signal.

This invention provides a fuel system in which such a fluid amplifier operates on a control signal based upon engine operating conditions and supplies fuel in accordance with the amplified signal. The drawing illustrates one embodiment of a fuel system which has fluid amplifiers to control fuel supplied to an engine in accordance with air flow to the engine. In the disclosed fuel system carburetor, air flow to the engine creates a venturi pressure signal which controls a stream of air pumped through a fluid amplifier to create an amplified air flow signal. This amplified air flow signal controls fuel flow through a second fluid amplifier. Further amplification of the signal occurs in the second amplifier through deflection of the fuel flow path. The amount of this deflection determines the amount of fuel supplied by the carburetor to the engine.

The details as Well as other objects and advantages of this invention are disclosed in the following description and in the above-discussed drawing.

Patented June 4, 1968 "ice Referring to the drawing, a carburetor 10 has an air inlet 12 controlled by a throttle 14 in the customary manner. A venturi 16 provides a restriction within air inlet 12 which reduces the pressure of the air flow therethrough to create a control signal related to the rate of air flow.

A fluid amplifier, indicated generally at 18, has an inlet 20 opening into an interaction region 21. Inlet 20 is connected to an air pump 22. Air flow from pump 22 provides a stream of air through amplifier 18 which is issued along a predetermined path within interaction region 21 and which has a predetermined energy state. The air stream is discharged from interaction region 21 through outlets 2d and 26. With the amplifier construction so far described, the proportion of air discharged from outlet 24 is determined by the location of the splitter 28.

As air flows through the carburetor inlet 12 and the venturi 16, a pressure drop is produced to create a signal which is transferred through a passage to a regulating or control port 32 in the amplifier 18. This pressure signal at control port 32 has an energy state much lower than that of the air stream issued from port 20 but defleets the air stream to change the proportion of air discharged through outlet 24. As air flow through the carburetor inlet 12 increases, the pressure in venturi 16 drops further; this reduces pressure sensed at control port 32 deflects more of the air flow through amplifier 18 to outlet 24.

A second regulating or bias port 34 in amplifier 18 is connected with atmosphere by a passage 36. Bias port 34 allows the control port 32. to measure the venturi depression relative to atmospheric pressure so that the air flow through outlet 24 Will be compensated for changes in the atmospheric pressure. That is, when atmospheric pressure increases, the low energy pressure signal at bias port 34 will be increased to deflect more of the air flow through amplifier 18 to outlet 24.

An amplifier which operates as described is known as a proportional amplifier since the proportion of fluid discharged through outlet 24 varies with the pressure drop across the fluid stream, i.e., with the pressure differential between bias port 34 and control port 32.

A second fluid amplifier, indicated generally by 38, has an inlet to which fuel is supplied from a tank 42 by a pump 44. As is well-known, at a predetermined rate, the fuel stream from inlet 40 through an interaction region 41 to an outlet as occurs in a laminar jet. However, when a disturbance caused by a signal having an energy state much lower than that of the jet is created in the jet, turbulence will result, and a portion of the fuel will bypass outlet 46 and be discharged through outlet 48.

By conducting the air flow discharged from outlet 24 of fluid amplifier 18 through a passage 50 to a control port 52 in a fluid amplifier 38, turbulence may be created in the laminar flow of fuel from inlet 49. The amount of turbulence created and thus the amount of fuel which bypasses outlet 46 is proportional to the air flow through control port 52.

In operation, therefore, air flow through the carburetor air inlet 12 and venturi 16 creates a pressure signal proportional to the rate of air flow. Amplifier 18 operates on this signal to produce an amplified signal of air flow through passage 56 which is related to air flow in the carburetor air inlet 12. The air flow signal resulting at control port 52 is further amplified in amplifier 38 by creating turbulence in the fuel flow from inlet 40. Fuel in proportion to the amount of turbulence bypasses outlet 46 and passes through the outlet 48 to the fuel inlet 54 for mixing with the air flow through the carburetor air inlet .12.

A bias port 56 in amplifier 38 allows discharge of the air flow from control port 52 to atmosphere through a passage 58. In addition, bias port 56 maintains a low energy pressure signal adjacent the inlet 40 related to atmospheric pressure. The air flow across the laminar fuel jet from inlet 40 is dependent upon the pressure signal maintained by bias port 56, and thus the turbulence created in the fuel jet is dependent upon the atmospheric pressure maintained at bias port 56.

This invention, by introducing components entirely unknown in the fuel system art heretofore, provides a simple and inexpensive arrangement for amplifying signals based on engine operating conditions and thereby allows a reduction in the complexity of the existing fuel systems. In addition, this invention provides means for amplifying control signals indicative of air flow to the engine so that fuel systems may accomplish a more sensitive and eflicient metering of the fuel supplied to the engine. It will be appreciated by those skilled in fuel system and fluid amplifier technologies that this invention may be utilized in many other arrangements to supply fuel to an engine.

I claim:

1. An internal combustion engine fuel system comprising a nozzle adapted to discharge fuel for mixture with air,

fluid amplifier means having an interaction region, and including an inlet port opening into said interaction region,

a source of regulated fluid connected to said inlet port to issue a fluid stream along a predetermined path within said interaction region, said fluid stream having a predetermined energy state,

a source of regulating fluid connected to said interaction region and supplying fluid the characteristics of which provide a fluid signal indicative of an engine demand for fuel and having an energy state substantially lower than the energy state of the fluid stream and which causes a variation in the path of the fluid stream within said interaction region,

said amplifier means further including outlet means opening from said interaction region for receiving the fluid stream and establishing a regulated fluid condition which varies in accordance with variations in the path of the fluid stream,

a source of fuel, and

means connecting said source of fuel to said nozzle and including means connected to said outlet means for governing flow through said nozzle in accordance with the regulated fluid condition.

2. The fuel system of claim 1 wherein said outlet means comprises a plurality of outlet ports and divider means to direct the fluid stream issued from said inlet port into said outlet ports in accordance with the variations in the path of the fluid stream and thereby establish a fluid condition in one of said outlet ports which varies in accordance with the regulating fluid signal.

3. The fuel system of claim 2 wherein said outlet means comprises a pair of outlet ports.

4. The fuel system of claim 1 wherein the pressure of the regulating fluid provides the fluid signal.

5. The fuel system of claim 4 wherein said source of regulating fluid comprises a source of air at atmospheric pressure.

6. The fuel system of claim 1 wherein said source of regulating fluid comprises an air inlet for air flow to the engine and means associated with said air inlet to create a fluid signal indicative of the rate of air flow through said air inlet.

7. The fuel system of claim 6 wherein said means associated with said air inlet comprises means to create a pressure characteristic indicative of the rate of air flow through said air inlet.

8. The fuel system. of claim 7 wherein said means associated with said air inlet comprises a venturi.

9. The fuel system of claim 8 which further comprises a source of air at atmospheric pressure and wherein said fluid amplifier means further includes a bias port connected to said source of air and opening into said interaction region and wherein the differential between the pressure characteristic created by said venturi and the pressure of said source of air is applied across the fluid stream within said interaction region to cause a variation in the path of the fluid stream.

10. The fuel system of claim 9 wherein said fluid amplifier means further includes a control port opening into said interaction region at a location opposite said bias port and a passage connecting said venturi to said control port.

11. The fuel system of claim 1 wherein said fluid amplifier means further includes a regulating port opening into said interaction region and wherein said source of regulating fluid is connected to said regulating port.

12. The method of operating an internal combustion engine fuel system having fluid amplifier means including an interaction region, an inlet port opening into said interaction region, and outlet means opening from said interaction region comprising issuing a stream of air from said inlet port along a predetermined path within said interaction region, said air stream having a predetermined energy state,

sensing a fluid signal indicative of an engine demand for fuel at a certain rate, said fluid signal having an energy state substantially lower than the energy state of said air stream,

amplifying said fluid signal by utilizing said fluid signal to cause a variation in the path of said air stream Within said interaction region and receiving said air stream in said outlet means and establishing a fluid condition in said outlet means which varies in accordance with variations in the path of said air stream, and supplying fuel to the engine in accordance with said fluid condition.

References Cited UNITED STATES PATENTS 1,625,997 4/1927 Gronkwist. 2,754,812 7/1956 Gianini 123--1 19 2,874,944 2/1959 Dolza 26 1- 36 3,258,023 6/1966 Bowles 137-8'1.5

FOREIGN PATENTS 1,257,050 2/1961 France.

694,387 7/195'3 Great Britain.

289,804 3/ 3 Switzerland.

OTHER REFERENCES Kompass, E. 1.: The State of the Art in Fluid Amplifiers, Control Engineering, January 1963, pp. 88-93, vol. 10.

HARRY B. THORNTON, Primary Examiner. T. R. MILES, Examiner. 

1. AN INTERNAL COMBUSTION ENGINE FUEL SYSTEM COMPRISING A NOZZLE ADAPTED TO DISCHARGE FUEL FOR MIXTURE WITH AIR, FLUID AMPLIFIER MEANS HAVING AN INTERACTION REGION, AND INCLUDING AN INLET PORT OPENING INTO SAID INTERACTION REGION, A SOURCE OF REGULATED FLUID CONNECTED TO SAID INLET PORT TO ISSUE A FLUID STREAM ALONG A PREDETERMINED PATH WITHIN SAID INTERACTION REGION, SAID FLUID STREAM HAVING A PREDETERMINED ENERGY STATE, A SOURCE OF REGULATING FLUID CONNECTED TO SAID INTERACTION REGION AND SUPPLYING FLUID THE CHARACTERISTICS OF WHICH PROVIDE A FLUID SIGNAL INDICATIVE OF AN ENGINE DEMAND FOR FUEL AND HAVING AN ENERGY STATE SUBSTANTIALLY LOWER THAN THE ENERGY STATE OF THE FLUID STREAM AND WHICH CAUSES A VARIATION IN THE PATH OF THE FLUID STREAM WITHIN SAID INTERACTION REGION, SAID AMPLIFIER MEANS FURTHER INCLUDING OUTLET MEANS OPENING FROM SAID INTERACTION REGION FOR RECEIVING THE FLUID STREAM AND ESTABLISHING A REGULATED FLUID CONDITION WHICH VARIES IN ACCORDANCE WITH VARIATIONS IN THE PATH OF THE FLUID STREAM, A SOURCE OF FUEL, AND MEANS CONNECTING SAID SOURCE OF FUEL TO SAID NOZZLE AND INCLUDING MEANS CONNECTED TO SAID OUTLET MEANS FOR GOVERNING FLOW THROUGH SAID NOZZLE IN ACCORDANCE WITH THE REGULATED FLUID CONDITION. 